A sanitary washing device that includes a radio wave sensor detecting a user is known. For example, the entrance of the user into a toilet room, the exit of the user from the toilet room, the user standing in front of an open toilet seat (e.g., the user performing standing urination), etc., can be detected by the radio wave sensor.
The sanitary washing device can execute functions of the sanitary washing device based on the detection result of the radio wave sensor. For example, when the sanitary washing device detects the user entering the toilet room and approaching the toilet, the sanitary washing device automatically opens the toilet lid. Also, for example, when the sanitary washing device detects that the user has finished standing urination and has moved away from the toilet, the sanitary washing device automatically closes the toilet seat and/or the toilet lid, automatically flushes the toilet, etc.
For example, a radio wave transmitter/receiver and a controller that is connected to the radio wave transmitter/receiver are provided in such a radio wave sensor. The radio wave transmitter/receiver radiates a radio wave for detecting an object to be detected (the user) and receives the reflected wave of the radio wave. The controller determines the state of the object to be detected based on the reflected wave received by the radio wave transmitter/receiver and outputs, to the main part of the sanitary washing device, a signal relating to the determination result. The sanitary washing device can execute the start or the end of the functions of the sanitary washing device based on the signal.
If the arrangement of the radio wave sensor is inappropriate, there are cases where the radio wave that is radiated from the radio wave transmitter/receiver is blocked, reflected, or refracted by a member of the sanitary washing device, etc.; thereby, the radio wave does not propagate easily toward the user. Therefore, there is a risk that the accuracy of detecting the user may decrease. For example, a resin that forms the toilet seat and/or the metal heater that is provided in the interior of the toilet seat affects the propagation of the radio wave in the case where the toilet seat is positioned at the front of the radio wave sensor. Therefore, a part of the radio wave radiated from the radio wave sensor may be obstructed from propagating in the direction of the user.